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7793 :: How do I get the fields/attributes of an object type at run time?

• halloleo (orginal) [2021-04-15T10:13:24+02:00] view original

  I am starting to dabble into type introspection. I have the following test program:

  
  import
    sugar,
    macros
  
  type
    MyInfo* = object
      fname*: string
      cname*: string
      ctype*: string
  
  var
    myInfoAttrs: seq[string]
  
  static:
    myInfoAttrs = collect(newSeq):
      for sym in getType(MyInfo)[2]: $sym
  
  echo myInfoAttrs
  Run

  I would like to _use the static sequence myInfoAttrs in my normal code, but I get "Error: cannot evaluate at compile time: myInfoAttrs". So I do something wrong here.

  Also, is there a way to access attributes/fields of MyInfo via dynamic strings? - I assume not, because Nim is statically compiled, but maybe there's a trick with macros?

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• DeletedUser (orginal) [2021-04-15T10:22:23+02:00] view original

  myInfoAttrs is a runtime address, you cannot use it at compile time (in the static block). You can still create the seq at compile time:

  import
    sugar,
    macros
  
  type
    MyInfo* = object
      fname*: string
      cname*: string
      ctype*: string
  
  var
    myInfoAttrs: seq[string]
  
  myInfoAttrs = static:
    collect(newSeq):
      for sym in getType(MyInfo)[2]: $sym
  
  echo myInfoAttrs
  Run

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• halloleo (orginal) [2021-04-16T07:06:00+02:00] view original

  Thanks @Hlaaftana! When I see your change, it is obvious, but I was banging my head against the keyboard instead...

  And I guess, fieldPairs is exactly what I was looking for!

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